Reinforced, molded, plastic parts, particularly fiberglass-reinforced plastics, are produced from resin-impregnated fiberglass composites which approximate the configuration of the intended molded plastic part. A fiberglass preform is often used when the intended molded part design is complex, including deep draws and/or contouring. By the term "preform," it is generally meant a fiber-reinforced mat or layer which, in association with other layers, is applied to a mold and subsequently shaped and cured. Unsaturated polyester molding resins are the most commonly used thermosetting resins, although epoxy, phenolic, and silicone molding resins can be used to obtain special properties. The most common reinforcements are fibers, particularly fiberglass fibers, although carbon and synthetic fibers can be used, as well as glass fibers and other micro configurations. Sheet molding compounds can be advantageously used in closed die molding operations and ordinarily comprise preformed composites of randomly oriented glass fiber, thermosetting resin, fillers, initiators, catalysts, thickening agents, and the like. Sheet molding compounds can be up to about one-quarter inch thick and are particularly useful for compression molding. Compression molding for complete parts, however, has the disadvantage that several pieces or strips of sheet molding compound or other preformed resin impregnated fiberglass patterns must be transported by hand and individually located in various cavities within the die, a tedious and time-consuming preparatory step. Resin-impregnated fiberglass composites are typically unsupported and readily susceptible to damage upon handling in addition to having tacky surfaces. Manual arrangement of composites within the mold cavity is time-consuming and difficult. Technological molding problems are encountered due to the first applied resin-impregnated strip being subjected to heat for a longer period of time than the last applied strip and thus premature cure can occur. Cure inhibitors are generally added to prevent premature reaction, but extend the cure time and hence extend the molding cycle.
The various problems associated with molding complex thermoset molded fiberglass parts have prompted various proposed means for transferring uncured lay-out or patterns to molding dies. Lay-out stations are provided adjacent to the molding presses where resin-impregnated configurations are laid out in the same form or pattern as will be arranged in the press.
An impaling transfer apparatus is disclosed in U.S. Pat. No. 4,015,872, where the apparatus includes spearhead elements adapted to penetrate resinous composites to a molding press. The spearheads are rotated axially after penetration of the composite to engage the material for lifting and transportation. Upon reaching the molding die, the spearheads are aligned with stripper plates and reverse rotated and, in conjunction with the stripper plates, the preformed lay-out is discharged into the mold.